1. Field of Invention
The present disclosure relates to flame retarding materials. More particularly, the present disclosure relates to non-dripping flame retarding materials.
2. Description of Related Art
Flame retardants are widely used in plastic and textile materials so as to bestow combustion-inhibiting or flame-resistant properties to the final products. Depending on the principal component, flame retardants can be categorized in to halogenated flame retardants, phosphorus-containing flame retardants, phosphorus and nitrogen containing flame retardants and inorganic flame retardants.
The principal component of the halogenated flame retardants is halocarbon such as polychlorinated biphenyl, chlorinated paraffin, polybrominated biphenyl, and polybromophenyl ether. Halogenated flame retardants are known to exhibit good flame-retarding efficacy and are highly compatible with plastic materials. Moreover, the halogenated flame retardants would not significantly affect the inherent properties of the plastic materials, and thus would not jeopardize the mechanical properties of the final products. Therefore, halogenated flame retardants are widely used in various plastic and textile products in the early days. During combustion, however, the halogenated flame retardants may produce black smokes that are sometimes corrosive; more particularly, some halogenated flame retardants may produce carcinogenic substances. In view of the safety concerns to the environment and human health, most halogenated flame retardants are banned for use in textile products, with only a small portion of halogenated flame retardants are allowed in plastic materials.
Common examples of phosphorus-containing flame retardants may include, but are not limited to red phosphorus, polyphosphate and ammonium polyphosphate. The phosphorus content of the red phosphorus may be up to 100%, and hence, theoretically, red phosphorus should be the most effective one among all the phosphorus-containing flame retardants. However, the appearance of the red phosphorus is usually black or red which together with its poor compatibility with plastic materials and poor processability limit its application in the plastic and textile fields. On the other hand, polyphosphate and ammonium polyphosphate are widely used in the textile field as flame retardants. However, in order to exhibit satisfactory fire retarding efficacy, the required content of such fire retardants is as high as 30 wt % which may not only increase the manufacturing cost but also decrease the spinnability of the material. In addition, phosphorus-containing flame retardants may cause dripping effect during combustion.
Phosphorus and nitrogen containing flame retardants, also known as intumescent fire retardants, are halogen-free flame retardants. Examples of intumescent fire retardants are ammonium polyphosphate, melamine (trimeric cyanamide) and pentaerythritol. The phosphorus and nitrogen containing flame retardants would increase the carbon source and acid source and swell upon heating. In addition, they produce less smoke and substantially no toxic gases during burning. However, the processability and weather resistance of the phosphorus and nitrogen containing flame retardants are less satisfactory, and hence, the properties thereof may change under the influences of the weather and environment. Moreover, phosphorus and nitrogen containing flame retardants may be separated from the matrix material, for example, while being damped or hydrolyzed.
Inorganic flame retardants include antimony trioxide, magnesium hydroxide, aluminium hydroxide, and zinc borate. These materials produce less smoke during combustion, and usually release substances such as water and carbon dioxide that are more environmentally friendly. However, the flame retarding efficacy of such inorganic materials is not as desirable as the organic fire retardants. Hence, the inorganic materials should be added in a substantially great amount to bestow a satisfactory flame retarding efficacy to the final product material. Besides, such inorganic materials are poorly compatible with thermoplastic materials such as resins, and hence they tend to aggregate within the thermoplastic materials.
In sum, various problems are experienced while using the flame retardants in the textile field. Such problems are, for example, poor in processability, washing fastness and mechanical properties. Regarding the finished flame retarding textiles, the textiles may not possess desirable transparency. Also, the textiles, during combustion, may not exhibit satisfactory flame retarding efficacy and may cause dripping effect.
In view of the foregoing, there exits an urgent need in the related field to provide a novel flame retarding materials that possess both desirable processing characteristics and flame retarding efficacy.